1. Field of the Invention
The present invention relates to a shield method and shield material for electronic component enclosures to prevent mixing noises to electronic components or transmitting noises from electronic components in electronic components receiving and transmitting by high frequencies, which are small types of about several millimeters like camera modules mounted in cell phones.
2. Description of the Prior Art
As for shielding electronic components, known conventional methods are the first method covering electronic component enclosures by shield cases of sheet metals and the second one resin-coating the surfaces of the enclosures.
Methods covering electronic component enclosures by shield cases of said sheet metals include a method in which an electrically-conductive thin metal plate like phosphor bronze is processed to be narrowed down and be formed like a case, and another method in which a thin metal plate is punched out by pressing and is then formed by clinch-process (Patent reference 1).
The method in which the thin metal plate is punched out by pressing and then formed by clinch-process is a shield type in which a top panel 11, a passage opening 12, a main lateral plate 13 and others are punched out to become designated shapes and a shield case 10 covers an electronic component 17 of square and other shapes from the head for shielding, as shown in FIGS. 7(a) and (b). Moreover, specifically, in the top panel 11, the passage opening 12 for the head to project above the electronic component 17, the main lateral plate 13, a sub-lateral plate 14 and a folded piece 15 of the four sides of the top panel 11 are punched by press. Next, a fold line 16 is processed with bending to make a cubic shield case and this covers from the top of the electronic component 17 to obtain a shield effect.
Besides it, similar shield cases are described in the patent references 2 and 3 and others.                [Patent reference 1] Japanese Provisional Publication No. 2005-276624        [Patent reference 2] Japanese Provisional publication No. 2006-294444        [Patent reference 3] Japanese Provisional publication No. 2007-36812        
In methods to form cases by drawing compound of conductive thin metal plates, because one metal plate is processed, although its shield effect is superior, the plate thickness is limited up to 0.1 mm and the shape at the drawing compound must be rounded, leading to become a large size overall. In addition, its deep drawing compound is so difficult that it is limited for shapes of small type electronic components.
In methods in which metal plates are punched out and clinched to form as shown in the patent references 1-3, the plate thickness is limited similarly to said drawing compound and the punching-out and clinching cannot be done smoothly. Moreover, it is necessary for the folding part to electrically connect by overlap space such as folded leaf in order to improve the shield effect, which makes it difficult to produce a small type.
In methods in which the surface of the enclosure is coated by resin, it is possible to make small and thin types because the external surface of the mold enclosure is coated by resin. When the enclosure consists of multiple components, it is necessary to conduct resin-coating before assembly and pass electricity at the connection sites among components, which leads to higher cost.
The objective of the present invention is to provide a shield method and shield material for enclosures of electronic components, which enables to make enclosure shapes flexible and make the components small and thin types.